1. Field of the Invention
The present invention relates to a puncture needle device for ultrasonic endoscope which is used while being inserted into an internal conduit of an ultrasonic endoscope.
2. Description of the Related Art
An ultrasonic endoscope with a pipe sleeve projecting from a control body of the ultrasonic endoscope, and a puncture needle device detachably attached to the pipe sleeve are disclosed in Japanese Unexamined Patent Publication 2005-137814.
This puncture needle device includes a cylindrical connecting body of the puncture needle device, a sheath which projects outwardly through an internal space of the cylindrical connecting body, and a puncture needle which is inserted into the sheath to be movable therein.
When the puncture needle device is used, an end of a cylindrical forceps plug, made of an elastic material such as rubber, is mounted to the pipe sleeve with the aid of the elasticity of the elastic material, and an end of the cylindrical connecting body of the puncture needle device is connected to the other end of the forceps plug with the aid of the elasticity of the forceps plug. Thereupon, the sheath (and the puncture needle) enters an internal conduit of the ultrasonic endoscope through the inside of the pipe sleeve, and the distal end of the sheath (and the distal end of the puncture needle) projects outwardly from a portion of the insertion portion of the ultrasonic endoscope in the vicinity of the distal end thereof.
In order for the operator to precisely manipulate the puncture needle device connected to the ultrasonic endoscope, tilting and rotation of the cylindrical connecting body of the puncture needle device relative to the pipe sleeve needs to be limited as much as possible.
However, in above-mentioned Japanese Unexamined Patent Publication 2005-137814, the puncture needle device tilts relative to the pipe sleeve (ultrasonic endoscope) of the ultrasonic endoscope when connected thereto via the forceps plug because the forceps plug disclosed therein is made of an elastic material.
In addition, attempts have been made to limit the rotation of the puncture needle device relative to the pipe sleeve about the central axis thereof by using frictional resistance produced between the forceps plug and each of the puncture needle device and the pipe sleeve. However, if a large torque is exerted on the puncture needle device, the puncture needle device cannot stand against this large torque solely by the aforementioned frictional resistance, thus the puncture needle device freely rotates about the central axis thereof.